On clusters serving Route via CRD (i.e. MicroShift), Route validation does not perform the same validation as on OCP.

Always

$ cat<<EOF | oc apply --server-side -f-
apiVersion: route.openshift.io/v1
kind: Route
metadata:
  name: hello-microshift
spec:
  to:
    kind: Service
    name: hello-microshift
EOF

route.route.openshift.io/hello-microshift serverside-applied

$ oc get route hello-microshift -o yaml

apiVersion: route.openshift.io/v1
kind: Route
metadata:
  annotations:
    openshift.io/host.generated: "true"
  creationTimestamp: "2022-11-11T23:53:33Z"
  generation: 1
  name: hello-microshift
  namespace: default
  resourceVersion: "2659"
  uid: cd35cd20-b3fd-4d50-9912-f34b3935acfd
spec:
  host: hello-microshift-default.cluster.local
  to:
    kind: Service
    name: hello-microshift
  wildcardPolicy: None

$ cat<<EOF | oc apply --server-side -f-
apiVersion: route.openshift.io/v1
kind: Route
metadata:
  name: hello-microshift
spec:
  to:
    kind: Service
    name: hello-microshift
  wildcardPolicy: ""
EOF

route.route.openshift.io/hello-microshift serverside-applied

The Route "hello-microshift" is invalid: spec.wildcardPolicy: Invalid value: "": field is immutable 

** This change will be inert on OCP, which already has the correct behavior. **